Contrary to the way you would port and prep an OHV engine, compression in a Flathead engine will begin to restrict breathing if a head is resurfaced too much. I would keep that to a minimum. By reducing the head volume, you also make the transition area smaller as well. This is the area that is between the cylinder and valves in a Flathead. As for porting and relieving, there are many thoughts on this, some are dated all the way back to when these engines were new, and others are more modern thinking with todays technology and techniques. Tex Smith's Flathead book can give you a good baseline for beginning such a chore, I would highly recommend it. Welcome to Inliners....
